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Waste water heat recovery

Heating, cooling and energy saving with helically wound pipes (Energy from wastewater and warmed up soil)

There is a new market in the energy sector for manufacturers of helically wound pipes. Besides the classic diversion of wastewater, you can now also recover the wastewater’s energy with helically wound pipes. The wastewater and the pipe surrounded warmed up soil are a huge useful source of heat. The available support hoses around the helically wound pipes form a huge heat exchanger. Due to a heat transfer medium (brine or water) that flows through the support hoses, you can withdraw the heat energy from the wastewater and soil or you can store redundant heat energy ,that is being left over from building cooling, in the soil.

Waste water heat recovery

Cold district heating- Energy source and profitable heat distribution with a system

The current most implemented extension version is the central hot water district heating with a flow temperature of 80-120°C and the respective losses during the heat distribution.

Decentralised district heating nets are based on heat pumps and are placed in every heat decreasing building as individual heat generating units. The heat pumps draw their energy from a mutual heat source loop, which is laid underground through the whole housing area. It forms the heat source net and is called “cold district heating” or “anergy net”. The loop itself serves as heat exchanger or ground collector. One or more additional heat sources, like soil, wastewater or ground water can inject energy with their own heat exchangers. The temperature in these heat source loops is on the temperature level of soil or below, that’s why it’s called “Cold district heating”.

The lower the temperatures of the heat distribution lines are, the lower is the heat loss opposite to the soil. If the temperatures are below the soil’s one, heat recovery is started (cold district heating). The rise in temperature for heating purposes happens in the decentralised heat pumps. Reversible heat pumps or chillers can also chill in the summer. The CO2 emission of such a system is pretty low. With the cold district heating’s system not only an advantageous use of environmental heat happens, but also a retention and recovery of heat loss.

Incorporation of helically wound pipes (soil bound wastewater heat exchanger) into the heat source loop

The system is being improved when, besides the geothermal energy and loops, further injecting heat sources, like the PE- helically wound pipes are being incorporated into the wastewater heat use system. The system consists of a standardised sewage pipe with an external heat exchanger. A heat transfer medium (brine or water) which –isolated from the system- withdraws heat from the wastewater and the pipe surrounded warmed up soil, flows through said heat exchanger. This wastewater heat is also injected into the loop. Thanks to reversible heat pumps or chillers the system can store the redundant heat loss from the building cooling in summer into the soil around the loop or the helically wound pipe. Supportively, other heat sources like a geothermal probe, energy sources like communal heating stations or solar heat can be incorporated into the heat source loop. Nevertheless it always has to be made sure that the heat source loop’s temperature.



Bernhard Läufle

Graduated business economist
Engineer HVAC
Expert in heat recovery from wastewater
Im Türmle 34
D-78224 Singen
Phone +49 172 4349971
Mail: Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!
skype: b.laeufle

Mr. Läufle is an international specialist for heat recovery from wastewater and soil.'
He is active in different colleges in the areas of research, development, distribution and teaching. He also is an appointed member of the DWA team “wastewater heat use”.